Medical and surgical implants are often placed in anatomic spaces where it is desirable for the implant to conform to the unique anatomy of the targeted anatomic space to secure a seal therein, preferably without disturbing or distorting the unique anatomy of said targeted anatomic space.
While the lumens of most hollow anatomic spaces are ideally circular, in fact the cross-sectional configurations of most anatomic spaces are at best ovoid, and may be highly irregular. Lumenal irregularity may be due to anatomic variations and/or to pathologic conditions that may change the shape and topography of the lumen and its associated anatomic wall.
Examples of anatomic spaces where such implants may be deployed include, but are not limited to, blood vessels, the heart, other vascular structures, vascular defects, the trachea, the oropharynx, the esophagus, the stomach, the duodenum, the ileum, the jejunum, the colon, the rectum, ureters, urethras, fallopian tubes, biliary ducts, pancreatic ducts, or other anatomic structures containing a lumen used for the transport of gases, blood, or other liquids or liquid suspensions within a mammalian body.
Among vascular effects that are addressed by some preferred embodiments of the present disclosure are thoracic and abdominal aortic aneurysms.
In order for a patient to be a candidate for existing endograft methods and technologies, a proximal neck of at least 15 mm of normal aorta must exist between the origin of the most inferior renal artery and the origin of the aneurysm in the case of abdominal aneurysms or the left subclavian artery for thoracic aortic aneurysms in order to permit an adequate seal. Similarly, at least 15 mm of normal vessel must exist distal to the distal extent of the aneurysm for an adequate seal to be achieved.
Migration of existing endografts has also been a significant clinical problem, potentially causing leakage and re-vascularization of aneurysms and/or compromising necessary vascular supplies to arteries such as the carotid, subclavian, renal, or internal iliac vessels. This problem has been partially addressed by some existing endograft designs, in which barbs or hooks have been incorporated to help retain the endograft at its intended site. However, these existing endograft designs are not removable and repositionable once they are deployed. Thus, once such an endograft has been placed, open surgery is necessary if there is failure due to leakage or undesired occlusion of other vascular structures.
Because of the limitations imposed by existing vascular endograft devices and endovascular techniques, approximately eighty percent of abdominal and thoracic aneurysms repaired in the U.S. are still managed though open vascular surgery, instead of the lower morbidity of the endovascular approach.